Methods for operating heat pump water heater appliances

ABSTRACT

Heat pump water heater appliances and operational methods therefor are provided. A method includes receiving a peak generation signal, and activating a secondary heating element of the heat pump water heater appliance when the peak generation signal is received. The method further includes activating a sealed system of the heat pump water heater appliance when the peak generation signal is received, and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

FIELD OF THE INVENTION

The present subject matter relates generally to heat pump water heaterappliances and methods for operating the same, and more particularly tocost and energy efficient heating of water within heat pump water heaterappliances.

BACKGROUND OF THE INVENTION

Water heater appliances generally operate to heat water within the waterheater appliance's tank to a set temperature. The set temperature isgenerally selected such that heated water within the tank is at leasthot enough for showering, washing hands, etc. Heat pump water heatersare gaining broader acceptance as a more economic andecologically-friendly alternative to electric and gas water heaters.Heat pump water heaters include a sealed system for heating water to theset temperature.

One issue with use of a sealed system is that, when the system isactivated, a warm-up period is typically required before normaloperation of the system commences. For example, an expansion valve ofthe system may cycle for a period of time (in some cases 2-3 minutes) tobalance the various pressures within the system before compressoroperation commences. Accordingly, slight delays in heating are incurredwhen typical sealed systems are utilized.

Heat pump water heater appliances generally receive power from autility, and in exemplary embodiments an electrical utility. Power, suchas electricity, is supplied by the utility to a structure, such as aresidential or commercial building. Additionally, utilities haverecently begun charging different prices for power at different timesdepending on the amount of power that is being required from theutility. At peak load times, when demand by consumers is in excess ofthe amount of power being generated, a higher price can be required ofconsumers by the utility. At peak generation times, when the amount ofpower being generated by the utility is in excess of the demand byconsumers, a lower price can be required of consumers by the utility.

It would be generally desirable to take advantage of lower costs duringpeak generation periods by operating the heat pump water heater at thesetimes. However, in some cases, periods of peak generation and peak loadcan occur in relatively short lengths of time, such as between 4 secondsand 10 minutes. Further, in some cases, it can take between 1 minute and5 minutes for the sealed system to warm-up. Accordingly, a peakgeneration period may have expired by the time that the sealed system isoperational to heat the water within the appliance.

Accordingly, improved heat pump water heater appliances and methods foroperating the same are desired. In particular, cost and energy efficientheat pump water heater appliance operations which take advantage of peakgeneration periods would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one embodiment, a method for operating a heat pumpwater heater appliance is provided. The method includes receiving a peakgeneration signal, and activating a secondary heating element of theheat pump water heater appliance when the peak generation signal isreceived. The method further includes activating a sealed system of theheat pump water heater appliance when the peak generation signal isreceived, and deactivating the secondary heating element when the sealedsystem is operational after activation or when a non-peak generationsignal is received subsequent to receipt of the peak generation signal.

In accordance with another embodiment, a heat pump water heaterappliance is provided. The heat pump water heater appliance includes atank defining a chamber, the tank further defining an inlet aperture andan outlet aperture. The heat pump water heater appliance furtherincludes a hot water conduit extending through the outlet aperture andin fluid communication with the chamber of the tank, the hot waterconduit configured for directing a flow of water out of the chamber ofthe tank, and a cold water conduit extending through the inlet apertureand in fluid communication with the chamber of the tank, the cold waterconduit configured for directing a flow of water into the chamber of thetank. The heat pump water heater appliance further includes a sealedsystem configured to heat water within the chamber of the tank, and asecondary heating element configured to heat water within the chamber ofthe tank. The heat pump water heater appliance further includes acontroller in communication with the sealed system and the secondaryheating element. The controller is configured for receiving a peakgeneration signal, and activating the secondary heating element when thepeak generation signal is received. The controller is further configuredfor activating the sealed system when the peak generation signal isreceived, and deactivating the secondary heating element when the sealedsystem is operational after activation or when a non-peak generationsignal is received subsequent to receipt of the peak generation signal.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures.

FIG. 1 provides a perspective view of a water heater appliance accordingto an exemplary embodiment of the present subject matter.

FIG. 2 provides a schematic view of certain components of the exemplarywater heater appliance of FIG. 1.

FIG. 3 illustrates a method for operating a water heater applianceaccording to an exemplary embodiment of the present subject matter.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

FIG. 1 provides a perspective view of a water heater appliance 100according to an exemplary embodiment of the present subject matter. FIG.2 provides a schematic view of certain components of water heaterappliance 100. As may be seen in FIGS. 1 and 2, water heater appliance100 includes a casing 102 and a tank 112 mounted within casing 102. Tank112 defines an interior volume 114 for heating water therein. Waterheater appliance 100 may include similar components, be constructed in asimilar manner to and/or operate in the manner described in U.S. Pat.No. 8,422,870 of Nelson et al., which is hereby incorporated byreference in its entirety.

Water heater appliance 100 also includes a cold water conduit 104 and ahot water conduit 106 that are both in fluid communication with tank 112within casing 102. As an example, cold water from a water source, e.g.,a municipal water supply or a well, enters water heater appliance 100through cold water conduit 104. From cold water conduit 104, such coldwater enters interior volume 114 of tank 112 wherein the water is heatedto generate heated water. Such heated water exits water heater appliance100 at hot water conduit 106 and, e.g., is supplied to a bath, shower,sink, or any other suitable feature.

As may be seen in FIG. 1, water heater appliance 100 extends between atop portion 108 and a bottom portion 109 along a vertical direction V.Thus, water heater appliance 100 is generally vertically oriented. Waterheater appliance 100 can be leveled, e.g., such that casing 102 is plumbin the vertical direction V, in order to facilitate proper operation ofwater heater appliance 100.

A drain pan 110 is positioned at bottom portion 109 of water heaterappliance 100 such that water heater appliance 100 sits on drain pan110. Drain pan 110 sits beneath water heater appliance 100 along thevertical direction V, e.g., to collect water that leaks from waterheater appliance 100 or water that condenses on an evaporator 128 ofwater heater appliance 100. It should be understood that water heaterappliance 100 is provided by way of example only and that the presentsubject matter may be used with any suitable water heater appliance.

Turning now to FIG. 2, water heater appliance 100 includes an upperheating element 118, a lower heating element 119 and a sealed system 120for heating water within interior volume 114 of tank 112. Thus, waterheater appliance 100 is commonly referred to as a “heat pump waterheater appliance.” Upper and lower heating elements 118 and 119 can beany suitable heating elements. For example, upper heating element 118and/or lower heating element 119 may be an electric resistance element,a microwave element, an induction element, or any other suitable heatingelement or combination thereof. Lower heating element 119 may also be agas burner, and water heater appliance 100 need not include upperheating element 118 when lower heating element 119 is a gas burner.

Sealed system 120 includes a compressor 122, a condenser 124, athrottling device 126 and an evaporator 128. Condenser 124 is thermallycoupled or assembled in a heat exchange relationship with tank 112 inorder to heat water within interior volume 114 of tank 112 duringoperation of sealed system 120. In particular, condenser 124 may be aconduit coiled around and mounted to tank 112. During operation ofsealed system 120, refrigerant exits evaporator 128 as a fluid in theform of a superheated vapor and/or high quality vapor mixture. Uponexiting evaporator 128, the refrigerant enters compressor 122 whereinthe pressure and temperature of the refrigerant are increased such thatthe refrigerant becomes a superheated vapor. The superheated vapor fromcompressor 122 enters condenser 124 wherein it transfers energy to thewater within tank 112 and condenses into a saturated liquid and/or highquality liquid vapor mixture. This high quality/saturated liquid vapormixture exits condenser 124 and travels through throttling device 126that is configured for regulating a flow rate of refrigeranttherethrough. Upon exiting throttling device 126, the pressure andtemperature of the refrigerant drop at which time the refrigerant entersevaporator 128 and the cycle repeats itself. In certain exemplaryembodiments, throttling device 126 may be an electronic expansion valve(EEV).

Water heater appliance 100 also includes a tank temperature sensor 130.Tank temperature sensor 130 is configured for measuring a temperature ofwater within interior volume 114 of tank 112. Tank temperature sensor130 can be positioned at any suitable location within or on water heaterappliance 100. For example, tank temperature sensor 130 may bepositioned within interior volume 114 of tank 112 or may be mounted totank 112 outside of interior volume 114 of tank 112. When mounted totank 112 outside of interior volume 114 of tank 112, tank temperaturesensor 130 can be configured for indirectly measuring the temperature ofwater within interior volume 114 of tank 112. For example, tanktemperature sensor 130 can measure the temperature of tank 112 andcorrelate the temperature of tank 112 to the temperature of water withininterior volume 114 of tank 112. Tank temperature sensor 130 may also bepositioned at or adjacent top portion 108 of water heater appliance 100,e.g., at or adjacent an inlet of hot water conduit 106.

Tank temperature sensor 130 can be any suitable temperature sensor. Forexample, tank temperature sensor 130 may be a thermocouple or athermistor. As may be seen in FIG. 2, tank temperature sensor 130 may bethe only temperature sensor positioned at or on tank 112 that isconfigured for measuring the temperature of water within interior volume114 of tank 112 in certain exemplary embodiments. In alternativeexemplary embodiments, additional temperature sensors may be positionedat or on tank 112 to assist tank temperature sensor 130 with measuringthe temperature of water within interior volume 114 of tank 112, e.g.,at other locations within interior volume 114 of tank 112.

Water heater appliance 100 further includes a controller 150 that isconfigured for regulating operation of water heater appliance 100.Controller 150 is in, e.g., operative, communication with upper heatingelement 118, lower heating element 119, compressor 122 (and thus sealedsystem 120 generally), and tank temperature sensor 130. Thus, controller150 may selectively activate upper and lower heating elements 118 and119 and/or compressor 122 in order to heat water within interior volume114 of tank 112, e.g., in response to signals from tank temperaturesensor 130 and other signals as discussed herein

It should be understood that controller 150 may be integrated withinwater heater appliance 100, in certain exemplary embodiments. However,in alternative exemplary embodiments, controller 150 may be separatefrom other components of water heater appliance 100 and be positionedoutside of casing 102. Thus, controller 150 may be positioned remotelyrelative to casing 102, e.g., within a building housing water heaterappliance 100. In such exemplary embodiments, controller 150 maywirelessly communicate with other components of water heater appliance100.

Controller 150 includes memory and one or more processing devices suchas microprocessors, CPUs or the like, such as general or special purposemicroprocessors operable to execute programming instructions ormicro-control code associated with operation of water heater appliance100. The memory can represent random access memory such as DRAM, or readonly memory such as ROM or FLASH. The processor executes programminginstructions stored in the memory. The memory can be a separatecomponent from the processor or can be included onboard within theprocessor. Alternatively, controller 150 may be constructed withoutusing a microprocessor, e.g., using a combination of discrete analogand/or digital logic circuitry (such as switches, amplifiers,integrators, comparators, flip-flops, AND gates, and the like) toperform control functionality instead of relying upon software.

Controller 150 may operate upper heating element 118, lower heatingelement 119 and/or compressor 122 in order to heat water within interiorvolume 114 of tank 112. As an example, a user may select or establish aset temperature, t_(s), for water within interior volume 114 of tank112, or the set temperature t_(s) for water within interior volume 114of tank 112 may be a default value. Based upon the set temperature t_(s)for water within interior volume 114 of tank 112, controller 150 mayselectively activate upper heating element 118, lower heating element119 and/or compressor 122 in order to heat water within interior volume114 of tank 112 to the set temperature t_(s) for water within interiorvolume 114 of tank 112. The set temperature t_(s) for water withininterior volume 114 of tank 112 may be any suitable temperature. Forexample, the set temperature t_(s) for water within interior volume 114of tank 112 may be between about one hundred degrees Fahrenheit andabout one hundred and eighty-degrees Fahrenheit. As used herein withregards to temperature approximations, the term “about” means within tendegrees of the stated temperature.

Controller 150 also includes a network interface (not shown). Thecontroller 150 of water heater appliance 100 may include any suitablecomponents for interfacing with one more networks, such as a network160. For example, the network interface may include transmitters,receivers, ports, controllers, antennas, or other suitable componentsfor interfacing with network 160. The network interface may establishcommunication with network 160 via a connection 152. Connection 152 maybe any suitable medium, e.g., wired or wireless.

Network 160 may be any type of communications network, such as a localarea network (e.g. intranet), wide area network (e.g. Internet), or somecombination thereof. In general, communication between controller 150and network 160 may be carried via associated network interfaces usingany type of connection, using a variety of communication protocols (e.g.TCP/IP, HTTP), encodings or formats (e.g. HTML, XML), and/or protectionschemes (e.g. VPN, secure HTTP, SSL). In particular, network 160 may bea wireless local area network (WLAN) configured to conform to IEEE802.11.

As may be seen in FIG. 2, controller 150 may receive data or informationfrom various sources via network 160. For example, controller 150 may bein communication with a utility 162 that is providing power to theappliance 100. In exemplary embodiments, the utility may be anelectrical utility which is providing electrical power to the appliance100. The utility 162 may send signals to the controller 150, in somecases via a network 160, to control operation of the appliance 100. Forexample, utility 162 may send signals regarding the demand status of theutility 162, i.e. whether the demand status is operating at peak load,peak generation, or normal operation (between peak load and peakgeneration). For example, utility 162 may send peak load signals andpeak generation signals (as well as normal operation signals). Inexemplary embodiments, the peak load and peak generation signals maycorrespond to different line frequencies; i.e. the frequency ofoscillations of alternating current being transmitted from the utilityto the end user and thus to the appliance 100. For example, in someembodiments, a peak generation signal may be a line frequency of greaterthan a normal line frequency, i.e. 50 Hertz or 60 Hertz. A peak loadsignal may be a line frequency of less than a normal line frequency,i.e. 50 Hertz or 60 Hertz. Accordingly, a non-peak generation signal maybe a signal that corresponds to normal operation or peak load operation,and may thus in some embodiments be considered to be a normal linefrequency or a frequency of less than a normal line frequency, i.e. ator below 50 Hertz or at or below 60 Hertz. In other embodiments, thepeak load and peak generation signals may be electronic signals received(either wirelessly or via a wired connection) by the controller 150,such as from the utility 100. In general, a peak load signal indicatesthat demand on the utility 162 is in excess of the amount of power beinggenerated, and may be associated with a relatively higher power price.In general, a peak generation signal indicates that the amount of powerbeing generated by the utility is in excess of the demand, and may beassociated with a relatively lower power price.

Notably, while in some embodiments controller 150 is configured, via awired or wireless connection, to receive electronic signals asdiscussed, in other embodiments, controller 150 may simply be configuredto receive line frequencies from the utility 162. In either case,controller 150 may receive signals in accordance with the presentdisclosure.

Signals as discussed above may be received by the controller 150. Thecontroller 150 may advantageously utilize the received signals tocontrol operation of the appliance 100. For example, the controller 150through measurement of the voltage oscillations may analyze the linefrequency, and may thus be instructed via the utility 162 demandresponse signal. Such instruction may include, as discussed herein,deactivating particular heat sources when the line frequency shows signsof sagging, indicating high demand, and is thus considered a peak loadsignal. Such instruction may further include, as discussed herein,activating particular heat sources when the line frequency shows signsof surging, indicating low demand, and is thus considered a peakgeneration signal. Such features of water heater appliance 100 arediscussed in greater detail below in the context of FIG. 3.

FIG. 3 illustrates a method 300 for operating a water heater appliancein accordance with one embodiment of the present disclosure. Method 300may be used to operate any suitable heat pump water heater appliance.For example, method 300 may be used to operate water heater appliance100. Thus, method 300 is discussed in greater detail below in thecontext of water heater appliance 100. In exemplary embodiments,controller 150 may be configured or programmed to implement varioussteps of method 300. Operation of an appliance 100 as discussed hereinmay advantageously be relatively cost and energy efficient by takingadvantage of peak generation periods to heat water within the appliance100.

Method 300 may include, for example, the step 310 of receiving a peakgeneration signal, such as from utility 162 as discussed above. Method300 may further include, for example, the step 320 of activating one ormore secondary heating element 118, 119 when the peak generation signalis received. Such activation may be performed upon receipt of the peakgeneration signal and in response to the peak generation signal. Suchactivation may cause heating of water within tank 112 by the secondaryheating elements 118, 119. In exemplary embodiments, the secondaryheating elements 118, 119 may be electrical resistance elements,although alternatively, other suitable secondary heating elements 118,119 as discussed herein may be utilized. Such activation mayadvantageously facilitate heating of water within the tank 112 duringpeak generation times, and thus in many cases at relatively lower costto the consumer.

Method 300 may further include, for example, the step 315 of increasinga set temperature t_(s) when the peak generation signal is received. Forexample, the set temperature t_(s) may be increased to a temperaturevalue above a predetermined value, i.e. a value set by the user or adefault value, as discussed above. In some embodiments, for example, theset temperature t_(s) may be increased to a maximum set temperaturevalue, i.e. a maximum value at which the set temperature t_(s) can beset. Step 315 in exemplary embodiments may occur before step 320.Further, in some embodiments, step 320 may occur at least partially as aresult of the occurance of step 315. In other words, because the settemperature t_(s) is increased, one or more secondary heating elementsmay be activated.

Method 300 may further include, for example, the step 330 of activatingthe sealed system 120 when the peak generation signal is received. Suchactivation may be performed upon receipt of the peak generation signaland in response to the peak generation signal. Notably, activation ofthe sealed system 120 may in some embodiments cause the sealed system120 to function in a “warm-up” state, rather than in an operationalstate. When the sealed system 120 is operational, the system 120 isperforming active heating operations as discussed herein. When thesealed system 120 is warming up, the system 120 is preparing to performactive heating operations, and for example, the throttling device 126 iscycling between open and closed positions to equalize pressures withinthe system 120. Notably, the compressor 122, may operate when the sealedsystem 120 is operational, but may not operate when the sealed system120 is warming up.

Method 300 may further include, for example, the step 340 ofdeactivating the one or more secondary heating elements 118, 119 whenthe sealed system 120 is operational after activation or when a non-peakgeneration signal is received, such as from the utility 162, subsequentto receipt of the peak generation signal. For example, in some cases,the sealed system 120 may become operational (after warming up) beforethe peak generation period has ended. In these cases, the secondaryheating elements 118, 119 may be deactivated, and the sealed system 120allowed to actively heat the water within the tank 112. Suchdeactivation may occur, for example, upon initiation of operation of thesealed system 120. In other cases, the peak generation period may endbefore the sealed system 120 becomes operational. In these cases, thesecondary heating elements 118, 119 may be deactivated to cease powerconsumption thereby. In exemplary embodiments, whichever case occursfirst after step 320 and 330 may cause the one or more secondary heatingelements 118, 119 to be deactivated.

Method 300 may further include, for example, the step 350 ofdeactivating the sealed system 120 when a non-peak generation signal isreceived, such as from the utility 162, subsequent to receipt of thepeak generation signal (i.e. subsequent to step 310). Such deactivationmay occur whether the sealed system 120 is operational or warming up,and may occur to cease power consumption thereby.

Method 300 may further include, for example, the step 335 of decreasingthe set temperature t_(s) when a non-peak generation signal is received.For example, the set temperature t_(s) may be decreased to a temperaturevalue below the value to which the set temperature t_(s) was previousincreased (i.e. in step 315). In some embodiments, the set temperaturet_(s) may be decreased to a predetermined value, i.e. a value set by theuser or a default value, as discussed above. Step 335 in exemplaryembodiments may occur before step 340 (when step 340 occurs due toreceipt of a non-peak generation signal) and/or step 350. Further, insome embodiments, step 340 (when step 340 occurs due to receipt of anon-peak generation signal) and/or step 350 may occur at least partiallyas a result of the occurance of step 335. In other words, because theset temperature t_(s) is decreased, the one or more secondary heatingelements and/or sealed system 120 may be deactivated.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for operating a heat pump water heater appliance, the method comprising: receiving a peak generation signal; activating a secondary heating element of the heat pump water heater appliance when the peak generation signal is received; activating a sealed system of the heat pump water heater appliance when the peak generation signal is received; and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.
 2. The method of claim 1, further comprising deactivating the sealed system when the non-peak generation signal is received subsequent to receipt of the peak generation signal.
 3. The method of claim 1, wherein the secondary heating element is an electrical resistance heating element.
 4. The method of claim 1, wherein the peak generation signal is a line frequency of above 60 Hertz.
 5. The method of claim 1, wherein the non-peak generation signal is a line frequency of at or below 60 Hertz.
 6. The method of claim 1, further comprising increasing a set temperature for the heat pump water heater appliance when the peak generation signal is received.
 7. The method of claim 6, wherein the set temperature is increased to a maximum set temperature value.
 8. The method of claim 1, further comprising decreasing the set temperature for the heat pump water heater appliance when the non-peak generation signal is received.
 9. The method of claim 8, wherein the set temperature is decreased to a predetermined set temperature value.
 10. A heat pump water heater appliance, the heat pump water heater appliance comprising: a tank defining a chamber, the tank further defining an inlet aperture and an outlet aperture; a hot water conduit extending through the outlet aperture and in fluid communication with the chamber of the tank, the hot water conduit configured for directing a flow of water out of the chamber of the tank; a cold water conduit extending through the inlet aperture and in fluid communication with the chamber of the tank, the cold water conduit configured for directing a flow of water into the chamber of the tank; a sealed system configured to heat water within the chamber of the tank; a secondary heating element configured to heat water within the chamber of the tank; a controller in communication with the sealed system and the secondary heating element, the controller configured for: receiving a peak generation signal; activating the secondary heating element when the peak generation signal is received; activating the sealed system when the peak generation signal is received; and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.
 11. The heat pump water heater appliance of claim 10, wherein the controller is further configured for deactivating the sealed system when the non-peak generation signal is received subsequent to receipt of the peak generation signal.
 12. The heat pump water heater appliance of claim 10, wherein the secondary heating element is an electrical resistance heating element.
 13. The heat pump water heater appliance of claim 10, wherein the peak generation signal is a line frequency of above 60 Hertz.
 14. The heat pump water heater appliance of claim 10, wherein the non-peak generation signal is a line frequency of at or below 60 Hertz.
 15. The heat pump water heater appliance of claim 10, wherein the controller is further configured for increasing a set temperature for the heat pump water heater appliance when the peak generation signal is received.
 16. The heat pump water heater appliance of claim 15, wherein the set temperature is increased to a maximum set temperature value.
 17. The heat pump water heater appliance of claim 10, wherein the controller is further configured for decreasing the set temperature for the heat pump water heater appliance when the non-peak generation signal is received.
 18. The heat pump water heater appliance of claim 17, wherein the set temperature is decreased to a predetermined set temperature value.
 19. The heat pump water heater appliance of claim 10, wherein the controller is in communication with a network, the network in communication with a utility.
 20. The heat pump water heater appliance of claim 19, wherein the controller is in wireless communication with the network. 